118 THE FAUNA OF 



tion of bright colouring with poisonous or noxious 

 quahties is of common occurrence in animals. 



The tjrpical tree frogs of the family Hylidae are 

 widely distributed over the globe, but are absent from 

 Africa south of the Sahara, from Arabia, and from 

 India. They have suctorial disks at the ends of their 

 toes, are usually protectively coloiu*ed in shades of 

 green, the tints varying with the surroundings, and. 

 have glands upon the under surface whereby they can 

 absorb water from the damp leaves on which they rest, 

 and thus obviate the necessity for seeking ponds to 

 moisten the skin. Their breeding habits are often 

 pecuUar. Other amphibians are not adapted for the 

 arboreal hfe. 



In regard to fresh-water fish we may note one or two 

 pecuhar forms, found in the streams of the tropical 

 forest, or on its seaward margin. The very pecuHar 

 double-breathing fishes, which are animals furnished 

 both with lungs and gills, are represented in the tropical 

 streams of Queensland by Cetatodus, in the tropical 

 streams of Africa by Protopterus, and in those of 

 South America by Lepidosiren. None of these animals 

 voluntarily quit the water, but the fact that the two 

 last named can breathe when buried in the mud as well 

 as when swimming in water adapts them for life in 

 tropical regions, where there is often a well-marked 

 alternation of wet and dry seasons. 



Even more curious are the habits of the mudskippers 

 (Periophthalmus), which haunt the mangrove swamps 

 and mud-flats on the shores of the Indian and Pacific 

 Oceans and off the coast of West Africa. These are 

 bony fish which are partially adapted for life on land. 

 The anterior fins are curiously modified, so that the fish 

 can cMmb about the supporting roots of the mangroves, 



